A top southern official vowed on Thursday to crack down on the brutal exploitation of immigrant farm hands following a shock report claiming that many were working in conditions of virtual slavery .

Nichi Vendola, who heads the regional government of Puglia on the heel of Italy, said he was horrified at the thought that "in Puglia, farm labourers can be hired illegally for a pittance and then kept in a modern form of slavery" .

"We intend to shed full light on these shady matters where all humanity has disappeared and a segment of the labour market has been transformed into a concentration camp accompanied by atrocious violence," said the leftist governor in a speech before Italian President Giorgio Napolitano .

Napolitano, who was in the Puglia capital city of Bari for the opening of a major trade fair, also commented on the issue, saying that the plight of the immigrant crop pickers was "beyond belief and an absurd throwback in time" .

The phenomenon came to public attention earlier this month, when Italian journalist Fabrizio Gatti published an article in news magazine L'Espresso about how he had posed as an illegal immigrant tomato picker on several farms around Foggia in Puglia .

Gatti described conditions in which workers were beaten and threatened and forced to toil long hours with almost no breaks, food or water .

He said the workers were paid extremely low wages and often not paid at all .

He said a common tactic employed by their bosses was to call in the police on pay day so that the immigrants would flee for fear of being arrested or deported .

The reporter said many of the workers were living in the open, sleeping on old mattresses, or inside barns with no toilets, running water, electricity or cooking facilities .

He said the immigrants were 'charged' for this accommodation by the farm owners, who deducted money from their pay .

Gatti, who triggered a storm in October with a similar report about conditions at an immigrant holding centre on the Sicilian island of Lampedusa, said that one farm owner refused to hire him because he had no immigrant girl friends to present to the boss .

He also cited the case of a Bulgarian who was almost beaten to death after complaining about conditions .

Gatti said the Bulgarian reported his case to the police but was expelled because he was in Italy illegally .

He said the abuses were common across the crop-growing areas of the south and were to a lesser degree also present in the north .

The article was followed up yesterday by a report in the La Repubblica daily saying that police in Poland had opened files on 119 Polish citizens who have disappeared in Italy over the past six years .

The daily said the missing had come to Italy to work, most of them as crop pickers, and had subsequently vanished .

Police in Bari are already investigating what they have termed the "anomalous" deaths of 15 immigrant tomato pickers - 14 Poles and a Lithuanian .

Several of them were found strangled while others were found burnt, drowned or run over .

Prosecutors involved in the probes released wiretapping evidence in which an Eastern European believed to be responsible for recruiting crop pickers is heard threatening to kill rebellious hires .

Furious over the escape of two of the workers, the man is quoted as saying: "They cannot be allowed to behave like this. I'm going into the countryside today and I'm going to kill one or two as an example to the rest" .

Since the Gatti article appeared, local government officials and police in Foggia have been carrying out spot inspections on tomato-growing farms .

Dozens of farm owners have been charged with hiring illegal immigrants and some with maltreating their workers .

The illegal workers, meanwhile, have been served with papers ordering them to leave the country .

Interior Minister Giuliano Amato has acknowledged that the sanctions faced by illegal immigrants leave them vulnerable to exploitation .

He said last week that he was considering amending Italy's immigration laws so that those who report cases of exploitation are granted residency permits .

Amato and national police chief Giovanni De Gennaro are to set up a committee tasked with combating forms of immigrant exploitation .

The committee will include members of the police and Carabinieri forces and will be presided by Alessandro Pansa, the immigration and border police central director .